We propose to systematically delineate each of the kidney components that participate in the action of antidiuretic hormone (ADH). The molecular events that take place between the ADH activation of adenyl cyclase and the actual increase in osmotic water reabsorption will be elucidated. Our experimental systems will include: plasma membranes, membrane vesicles, and isolated whole cells from porcine kidney. Attempts will be made to identify proteins that are either phosphorylated or dephosphorylated under the influence of the cyclic adenosine monophosphate that is produced by the ADH activation of adenyl cyclase. With the use of specific inhibitors, we uill also assess the possible involvement of microtubular protein, microfilament protein, and key glycoproteins in the ADH scheme. An emphasis will also be given to elucidating the role of changes in calcium metabolism that may be an integral facet of the ADH effect. Spectral probes of membrane conformation changes and water permeability will be used to correlate the biochemical effects of each component with molecular interactions and the physiologic effect of ADH. Ultimately, we hope to be able to define the simplest system possible that can be reconstituted to completely illustrate the biochemical events that coincide with the ADH mediated water reabsorption from the kidney.